Aircraft: LIGHT TRANSPORT; LOW WING; 2 TURBOJET ENG
Phase of flight: Final Approach
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy

I had Aircraft X in a VFR pattern with right closed traffic. Aircraft Y was inbound from the southeast IFR. I initially saw a copter on the arrival list and believed the helicopter would arrive first; but then discovered it looked like the approach controller was keeping the jet traffic fast and was going to make Aircraft Y first. My plan then was to have Aircraft Y number 1 for Runway 30L and keep Aircraft X on Runway 30R. Aircraft Y was not switched prior 6 miles of the airport; as the LOA specifies. I quickly decided I was not comfortable with the traffic situation at all (Aircraft Y was really high and fast on final and not talking to me) and instructed Aircraft X to remain on the downwind for the traffic. Aircraft Y was in my airspace descending out of 8;000 feet; if I recall; I was finally able to reach Aircraft Y near a 3 mile final; around 7;800 feet. The pilot checked on and advised he wanted at least one 360 for descent. I instructed Aircraft Y to fly runway heading; and later confirmed he should climb to 8;000 feet. I asked the CIC to coordinate missed approach instructions; and was advised to assign him turn right heading 020. Once Aircraft Y was turning to the heading; I switched him back to departure for resequencing (a helicopter was east of the airport being vectored for an approach). After being sequenced for another approach; Aircraft Y landed without further incident. I'm not sure why the approach controller decided to try to keep Aircraft Y high and fast with the IFR helicopter traffic rather close to the final ahead; unfortunately; it seemed the pilot had virtually no other option than a go-around for maneuvers to descend back to the final. This was a situation where it was critical that I had communication/control at the proper point (6-15NM from the airport) so that I could call traffic and sequence the two turbojets. (The CIC also filed a report for the event). I understand that there are times the approach controller determines they cannot switch an aircraft by the 6 mile point (traffic conflict; pilot can't see the airport for the visual approach; etc.); but these situations either need to be coordinated immediately or an alternative course of action should be taken to prevent penetration of our Class D airspace. In the end; I was very glad that I did not hesitate to follow my instincts and took a conservative approach to control the aircraft I was talking to; by not allowing the Aircraft X to turn final until I was able to communicate and control the other inbound. I was also quite appreciative to have a CIC who was actively engaged in monitoring my complex operation and ensuring I was not becoming too overloaded. Since I determined I was too busy scanning and issuing control instructions to also safely do landline coordination; he was able to immediately assist me by asking the approach controller to switch the inbound traffic and then quickly coordinate missed approach instructions for me to resolve the conflict safely.In hindsight; another alternative may have been to try to coordinate getting the approach controller to clear the arriving aircraft to the other runway. However; I'm not sure if either one of us would have had the time to effectively coordinate this due to both our respective traffic situations. Once the traffic decreased later; the approach controller called on the line to apologize for Aircraft Y getting switched so late. I advised him that I simply had a lot of other traffic I was working when I wanted to talk to Aircraft Y; but in the end; everything was fine (I try to maintain a positive relationship between our tower and the approach controllers whenever possible). BJC Local Controller describes a conflict with two arrival aircraft that he resolves by keeping one of the aircraft on an extended downwind.